Add Drive.MetadataDBValidityCheckFailureReason UMA histogram

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 9d1e5082b4b1bdad7aab90f88fd355ffb4f439fd..9421f5a3264a44bad864b95b6d24ddb58ed48936 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -5490,6 +5490,17 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Drive.MetadataDBValidityCheckFailureReason"
+    enum="DriveMetadataDBValidityCheckFailureReason">
+  <owner>bengold@chromium.org</owner>
+  <owner>hashimoto@chromium.org</owner>
+  <summary>
+    Reason of drive resource metadata database validity check failure. Recorded
+    when the validity check fails during Drive metadata initialization triggered
+    by profile initialization.
+  </summary>
+</histogram>
+
 <histogram name="Drive.MetadataDBVersionBeforeUpgradeCheck">
   <owner>joshwoodward@google.com</owner>
   <summary>
@@ -38211,6 +38222,17 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="9" label="Cannot open existing DB. Created new DB."/>
 </enum>
 
+<enum name="DriveMetadataDBValidityCheckFailureReason" type="int">
+  <int value="0" label="Invalid header"/>
+  <int value="1" label="Broken ID entry"/>
+  <int value="2" label="Broken entry"/>
+  <int value="3" label="Invalid local ID"/>
+  <int value="4" label="Invalid parent ID"/>
+  <int value="5" label="Broken child map"/>
+  <int value="6" label="Child entry count mismatch"/>
+  <int value="7" label="Iterator error"/>
+</enum>
+
 <enum name="EAPInnerProtocol" type="int">
   <int value="0" label="UNKNOWN"/>
   <int value="1" label="NONE"/>